Syzygium australe extracts exhibit significant antioxidant and antidiabetic properties: a comprehensive analysis of the phytoconstituents

Abstract

Background

Medicinal plants are well known for their health benefits. Syzygium australe (Brush Cherry) is considered a health-promoting food due to its high antioxidant capacity, which may help prevent cancer, cardiovascular diseases, and neurological disorders. Additionally, S. australe exhibits antidiabetic and antiobesity properties.

Aim

This study reviews the antioxidant and antidiabetic activities of S. australe fractions, along with their key phytoconstituents.

Materials and methods

The antioxidant activity of S. australe crude extract and fractions was assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl-hydrate), ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)), FIC (ferrozine iron metal chelation), and FRAP (ferric reducing antioxidant power) assays. Their antidiabetic activity was evaluated using α-glucosidase, α-amylase, and lipase inhibition assays. Additionally, their TFC (total flavonoid content) and TPC (total phenolic content) were determined. The secondary metabolites were analysed using Triple TOF UPLC-ESI–MS/MS (ultra-performance liquid chromatography-electrospray ionization-time of flight-mass spectrometry).

Results

Our findings, for the first time, reveal that various S. australe extracts exhibit strong antidiabetic and antioxidant properties. The butanol and ethyl acetate fractions had the highest antidiabetic activity. Their respective IC₅₀ values against α-glucosidase, α-amylase, and lipase were 0.11–0.14 µg/mL, 0.06–0.09 µg/mL, and 26.5–30.79 ng/mL, respectively. Also, they showed powerful antioxidant activity. The IC₅₀ values of the ethyl acetate (19.93 ± 1 μg/mL) and butanol (38.7 μg/mL) fractions were significantly lower than those of the reference compounds, Trolox (24.42 ± 0.87 μg/mL) in the DPPH assay and EDTA (Ethylenediaminetetraacetic acid) (39.7 μg/mL) in the ferrozine iron metal chelation assay, respectively. They had a higher amount of TPC (397.65 ± 14.78, 253.32 ± 10.78 µg GAE/mg sample) and TFC (97.89 ± 4.98, 23.14 ± 1.11 µg RE/mg sample) of ethyl acetate and butanol, respectively. The significant phenolic and flavonoid substances found in these extracts may account for their strong antioxidant activity. Triple TOF UPLC-ESI–MS/MS analysis detected 18 phenolic acids, 19 derivatives, and 39 flavonoids. As a way to prevent or treat various disorders, these two extracts additionally served as a great source of antioxidant phytochemicals.

Conclusion

Ultimately, our findings strongly suggest that the phenolics of S. australe may be valuable for the development of antioxidant and antidiabetic medications.